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  • 201.
    Broitman, Esteban
    et al.
    Carnegie Mellon University, Pittsburgh, PA, USA .
    Neihardt, Jörg
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Fullerene-like Carbon Nitride: A New Carbon-based Tribological Coating2008Inngår i: Tribology of Diamond-Like Carbon Films: Fundamentals and Applications, Springer, 2008, 1, s. 620-653Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    In 1994, researchers at Linköping University discovered the fullerene-like allotrope of carbon nitride (FL-CNx) by using reactive magnetron sputtering in a nitrogen-containing atmosphere at rather low ion energy assistance. FL-CNx is a predominantly sp2-hybridized material with nitrogen structurally incorporated either substitutionally in a graphite sheet or in a pyridine-like manner, which initiates bending by formation of pentagons and cross-linking, respectively. The assumed nitrogen-induced cross-linkage between the sheets contributes considerably to the strength of FL-CNx by preventing interplanar slip. This results in an extremely fracture tough, elastic, and compliant material, which deforms by reversible bond rotation and bond angle deflection rather than slip and bond breaking.

  • 202.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tengdelius, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hangen, Ude D.
    Hysitron Inc., Minneapolis, Minnesota, USA.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Högberg, Hans
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    High-temperature nanoindentation of epitaxial ZrB2 thin films2016Inngår i: Scripta Materialia, ISSN 1359-6462, E-ISSN 1872-8456, Vol. 124, s. 117-120Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We use in-situ heated nanoindentation to investigate the high-temperature nanomechanical properties of epitaxial and textured ZrB2 films deposited by magnetron sputtering. Epitaxial films deposited on 4H-SiC(0001) show a hardness decrease from 47 GPa at room temperature to 33 GPa at 600 °C, while the reduced elastic modulus does not change significantly. High resolution electron microscopy (HRTEM) with selected area electron diffraction of the indented area in a 0001-textured film reveals a retained continuous ZrB2 film and no sign of crystalline phase transformation, despite massive deformation of the Si substrate. HRTEM analysis supports the high elastic recovery of 96% in the films.

    Fulltekst (pdf)
    fulltext
  • 203.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Yousuf Soomro, Muhammad
    Linköpings universitet, Institutionen för teknik och naturvetenskap. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Willander, Magnus
    Linköpings universitet, Institutionen för teknik och naturvetenskap, Fysik och elektroteknik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nanoscale piezoelectric response of ZnO nanowires measured using a nanoindentation technique2013Inngår i: Physical Chemistry, Chemical Physics - PCCP, ISSN 1463-9076, E-ISSN 1463-9084, Vol. 15, nr 26, s. 11113-11118Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report the piezoelectric properties of ZnO nanowires (NWs) obtained by using a nanoindenter with a conductive boron-doped diamond tip. The direct piezoelectric effect was measured by performing nanoindentations under load control, and the generated piezoelectric voltage was characterized as a function of the applied loads in the range 0.2-6 mN. The converse piezoelectric effect was measured by applying a DC voltage to the sample while there was a low applied force to allow the tip being always in physical contact with the NWs. Vertically aligned ZnO NWs were grown on inexpensive, flexible, and disposable paper substrates using a template-free low temperature aqueous chemical growth method. When using the nanoindenter to measure the direct piezoelectric effect, piezopotential values of up to 26 mV were generated. Corresponding measurement of the converse piezoelectric effect gave an effective piezoelectric coefficient d(33)(eff) of similar to 9.2 pm V-1. The ZnO NWs were also characterized using scanning electron microscopy, X-ray diffraction, and high-resolution transmission electron microscopy. The new nanoindentation approach provides a straightforward method to characterize piezoelectric material deposited on flexible and disposable substrates for the next generation of nanodevices.

    Fulltekst (pdf)
    fulltext
  • 204.
    Broitman, Esteban
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan. Laboratorio de Peliculas Delgudas, Facultad de Ingenieria, Universidad de Buenos Aires, Buenos Aires, Argentilta.
    Zimmerman, Rosa
    Laboratorio de Peliculas Delgudas, Facultad de Ingenieria, Universidad de Buenos Aires, Buenos Aires, Argentilta.
    Resistividad Eléctrica Residual en Péliculas Delgadas [Residual Electrical Resistivity in Thin Metal Films]1994Inngår i: Anales AFA, ISSN 1850-1158, Vol. 5, nr 1, s. 280-282Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [es]

    Ha sido bien establecido que la resistividad de las películas, delgadas depende fuertemente de su estructura. Para entender mejor dicha influencia se comparó la resistividad residual (0°K) de películas obtenidas por evaporación en vacío y por ion-plating. Las películas obtenidas por esta última técnica se caracterizan por tener un diámetro de grano menor y mayor uniformidad en tamaño y forma de los granos. La resistividad residual fue determinada midiendo la resistividad a distintas temperaturas para muestras de distintos espesores. El tamaño de grano se obtuvo por microscopía electrónica de transmisión.

  • 205.
    Bruckner, Barbara
    et al.
    Uppsala Univ, Sweden; Johannes Kepler Univ Linz, Austria.
    Hans, Marcus
    Rhein Westfal TH Aachen, Germany.
    Nyberg, Tomas
    Uppsala Univ, Sweden.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bauer, Peter
    Uppsala Univ, Sweden; Johannes Kepler Univ Linz, Austria.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Electronic excitation of transition metal nitrides by light ions with keV energies2020Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 32, nr 40, artikkel-id 405502Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We investigated the specific electronic energy deposition by protons and He ions with keV energies in different transition metal nitrides of technological interest. Data were obtained from two different time-of-flight ion scattering setups and show excellent agreement. For protons interacting with light nitrides, i.e. TiN, VN and CrN, very similar stopping cross sections per atom were found, which coincide with literature data of N(2)gas for primary energies <= 25 keV. In case of the chemically rather similar nitrides with metal constituents from the 5(th)and 6(th)period, i.e. ZrN and HfN, the electronic stopping cross sections were measured to exceed what has been observed for molecular N(2)gas. For He ions, electronic energy loss in all nitrides was found to be significantly higher compared to the equivalent data of N(2)gas. Additionally, deviations from velocity proportionality of the observed specific electronic energy loss are observed. A comparison with predictions from density functional theory for protons and He ions yields a high apparent efficiency of electronic excitations of the target for the latter projectile. These findings are considered to indicate the contributions of additional mechanisms besides electron hole pair excitations, such as electron capture and loss processes of the projectile or promotion of target electrons in atomic collisions.

  • 206. Brunell, I.F.
    et al.
    Pichon, L.
    Lab. de Mëtallurgie Physique, UMR 6630-CNRS, Téléport 2, Boulevard Pierre et Marie Curie, Chasseneuil Cédex, France.
    Hellgren, N.
    Materials Research Laboratory, University of Illinois, 104 S. Goodwin Ave., Urbana, IL 61801, United States.
    Czigany, Zsolt
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Neidhardt, Jörg
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    In-situ  stress measurement during the deposition of CN x thin films by unbalanced magnetron sputtering; formation of high levels of stress with 28 eV ion irradiation2004Inngår i: Philosophical Magazine Letters, ISSN 0950-0839, E-ISSN 1362-3036, Vol. 84, nr 6, s. 395-403Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Stress development during growth of CN x films by unbalanced magnetron sputtering has been investigated with an in-situ laser deflection technique. The stress is initially tensile, then it becomes compressive, reaching a maximum of as much as 7 GPa. These are anomalously high stress levels compared with pure carbon, considering the low ion energies (28 eV) and ion-to-neutral arrival rate ratio (<1) employed. This phenomenon is explained by the formation of a fullerene-like microstructure and nitrogen substitution at the growth surface. An accompanying increased reactivity of carbon atoms promotes sp3 bonding or other cross-linking of curved basal planes with resulting film densification.

  • 207.
    Buchholt, Kristina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Ghandi, R
    Royal Institute Technology, KTH.
    Domeij, M
    Royal Institute Technology, KTH.
    Zetterling, C M
    Royal Institute Technology, KTH.
    Behan, G
    Trinity College Dublin.
    Zhang, H
    Trinity College Dublin.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Growth and characterization of epitaxial Ti3GeC2 thin films on 4H-SiC(0001)2012Inngår i: Journal of Crystal Growth, ISSN 0022-0248, E-ISSN 1873-5002, Vol. 343, nr 1, s. 133-137Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epitaxial Ti3GeC2 thin films were deposited on 4 degrees off-cut 4H-SiC(0001) using magnetron sputtering from high purity Ti, C, and Ge targets. Scanning electron microscopy and helium ion microscopy show that the Ti3GeC2 films grow by lateral step-flow with {11 (2) over bar0} faceting on the SiC surface. Using elastic recoil detection analysis, atomic force microscopy, and X-Ray diffraction the films were found to be substoichiometric in Ge with the presence of small Ge particles at the surface of the film.

    Fulltekst (pdf)
    fulltext
  • 208.
    Buchholt, Kristina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Jensen, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Step-flow growth of nanolaminate Ti3SiC2 epitaxial layers on 4H-SiC(0 0 0 1)2011Inngår i: SCRIPTA MATERIALIA, ISSN 1359-6462, Vol. 64, nr 12, s. 1141-1144Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epitaxial Ti3SiC2(0 0 0 1) films were deposited on 4 degrees off-cut 4H-SiC(0 0 0 1) wafers using magnetron sputtering. A lateral step-flow growth mechanism of the Ti3SiC2 was discovered by X-ray diffraction, elastic recoil detection analysis, atomic force microscopy and electron microscopy. Helium ion microscopy revealed contrast variations on the Ti3SiC2 terraces, suggesting a mixed Si and Ti(C) termination. Si-rich growth conditions results in Ti3SiC2 layers with pronounced {1 1 (2) over bar 0) faceting and off-oriented TiSi2 crystallites, while stoichiometric growth yields truncated {1 (1) over bar 0 0) terrace edges.

    Fulltekst (pdf)
    fulltext
  • 209.
    Buchholt, Kristina
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ghandi, R
    Royal Institute of Technology.
    Domeij, M
    Royal Institute of Technology.
    Zetterling, C-M
    Royal Institute of Technology.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tillämpad Fysik. Linköpings universitet, Tekniska högskolan.
    Ohmic contact properties of magnetron sputtered Ti3SiC2 on n- and p-type 4H-silicon carbide2011Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 98, nr 4, s. 042108-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Epitaxial Ti3SiC2 (0001) thin film contacts were grown on doped 4H-SiC (0001) using magnetron sputtering in an ultra high vacuum system. The specific contact resistance was investigated using linear transmission line measurements. Rapid thermal annealing at 950 degrees C for 1 min of as-deposited films yielded ohmic contacts to n-type SiC with contact resistances in the order of 10(-4) Omega cm(2). Transmission electron microscopy shows that the interface between Ti3SiC2 and n-type SiC is atomically sharp with evidence of interfacial ordering after annealing.

    Fulltekst (pdf)
    ApplPhysLett
  • 210.
    Bugnet, M
    et al.
    University of Poitiers, France .
    Mauchamp, V
    University of Poitiers, France .
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Jaouen, M
    University of Poitiers, France .
    Cabioch, T
    University of Poitiers, France .
    Contribution of core-loss fine structures to the characterization of ion irradiation damages in the nanolaminated ceramic Ti3AlC22013Inngår i: Acta Materialia, ISSN 1359-6454, E-ISSN 1873-2453, Vol. 61, nr 19, s. 7348-7363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of low-energy ion irradiation on the nanolaminated Ti3AlC2 is investigated by means of X-ray diffraction, transmission electron microscopy, electron energy loss and X-ray absorption spectroscopy. The chemical sensitivity and local order probing from core-loss edges provide new insights into the structural modifications induced under irradiation. From the analysis of the C K energy loss near-edge structure and Al K X-ray absorption near-edge structure by ab initio calculations, the influence of the layered structure of this compound on the irradiation damage is demonstrated, and damage is found to be preferentially localized in the aluminum planes of the structure. On the basis of comparisons between calculations and experimental spectra, a structural model is proposed for the irradiated state. This study emphasizes the utility of core-loss fine structure analysis to enhance understanding of ion irradiation-induced damage in complex crystalline materials.

    Fulltekst (pdf)
    fulltext
  • 211.
    Bunnfors, Kalle
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Abrikossova, Natalia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kilpijarvi, Joni
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten. Univ Oulu, Finland.
    Eriksson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Juuti, Jari
    Univ Oulu, Finland.
    Halonen, Niina
    Univ Oulu, Finland.
    Brommesson, Caroline
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Lloyd Spetz, Anita
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Sensor- och aktuatorsystem. Linköpings universitet, Tekniska fakulteten.
    Uvdal, Kajsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Nanoparticle activated neutrophils-on-a-chip: A label-free capacitive sensor to monitor cells at work2020Inngår i: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, SENSORS AND ACTUATORS B-CHEMICAL, Vol. 313, artikkel-id 128020Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Neutrophil granulocytes are the most abundant white blood cells in mammals and vital components of the immune system. They are involved in the early phase of inflammation and in generation of reactive oxygen species. These rapid cell-signaling communicative processes are performed in the time frame of minutes. In this work, the activity and the response of neutrophil granulocytes are monitored when triggered by cerium-oxide based nanoparticles, using capacitive sensors based on Lab-on-a-chip technology. The chip is designed to monitor activation processes of cells during nanoparticle exposure, which is for the first time recorded on-line as alteration of the capacitance. The complementary metal oxide semiconductor engineering chip design is combined with low temperature co-fired ceramic, LTCC, packaging technology. The method is label free and gently measures cells on top of an insulating surface in a weak electromagnetic field, as compared to commonly used four-point probes and impedance spectroscopy electric measurements where electrodes are in direct contact with the cells. In summary, this label free method is used to measure oxidative stress of neutrophil granulocytes in real time, minute by minute and visualize the difference in moderate and high cellular workload during exposure of external triggers. It clearly shows the capability of this method to detect cell response during exposure of external triggers. In this way, an informationally dense non-invasive method is obtained, to monitor cells at work.

  • 212.
    Burcea, Razvan
    et al.
    Univ Poitiers, France.
    Barbot, Jean-Francois
    Univ Poitiers, France.
    Renault, Pierre-Olivier
    Univ Poitiers, France.
    Eyidi, Dominique
    Univ Poitiers, France.
    Girardeau, Thierry
    Univ Poitiers, France.
    Marteau, Marc
    Univ Poitiers, France.
    Giovannelli, Fabien
    Univ Tours, France.
    Zenji, Ahmad
    Univ Bordeaux, France.
    Rampnoux, Jean-Michel
    Univ Bordeaux, France.
    Dilhaire, Stefan
    Univ Bordeaux, France.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    le Febvrier, Arnaud
    Univ Poitiers, France.
    Correction: Influence of Generated Defects by Ar Implantation on the Thermoelectric Properties of ScN (vol 5, pg 11025, 2022)2023Inngår i: ACS Applied Energy Materials, E-ISSN 2574-0962Artikkel i tidsskrift (Annet vitenskapelig)
  • 213.
    Burcea, Razvan
    et al.
    Univ Poitiers ENSMA, France.
    Barbot, Jean-Francois
    Univ Poitiers ENSMA, France.
    Renault, Pierre-Olivier
    Univ Poitiers ENSMA, France.
    Eyidi, Dominique
    Univ Poitiers ENSMA, France.
    Girardeau, Thierry
    Univ Poitiers ENSMA, France.
    Marteau, Marc
    Univ Poitiers ENSMA, France.
    Giovannelli, Fabien
    Univ Tours, France.
    Zenji, Ahmad
    Univ Bordeaux, France.
    Rampnoux, Jean-Michel
    Univ Bordeaux, France.
    Dilhaire, Stefan
    Univ Bordeaux, France.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Influence of Generated Defects by Ar Implantation on the Thermoelectric Properties of ScN2022Inngår i: ACS Applied Energy Materials, E-ISSN 2574-0962, Vol. 5, nr 9, s. 11025-11033Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Nowadays, making thermoelectric materials more efficient in energy conversion is still a challenge. In this work, to reduce the thermal conductivity and thus improve the overall thermoelectric performances, point and extended defects were generated in epitaxial 111-ScN thin films by implantation using argon ions. The films were investigated by structural, optical, electrical, and thermoelectric characterization methods. The results demonstrated that argon implantation leads to the formation of stable defects (up to 750 K operating temperature). These were identified as interstitial-type defect dusters and argon vacancy complexes. The insertion of these specific defects induces acceptor-type deep levels in the band gap, yielding a reduction in the free-carrier mobility. With a reduced electrical conductivity, the irradiated sample exhibited a higher Seebeck coefficient while maintaining the power factor of the film. The thermal conductivity is strongly reduced from 12 to 3 W.m(-1). K-1 at 300 K, showing the influence of defects in increasing phonon scattering. Subsequent high-temperature annealing at 1573 K leads to the progressive evolution of these defects: the initial dusters of interstitials evolved to the benefit of smaller dusters and the formation of bubbles. Thus, the number of free carriers, the resistivity, and the Seebeck coefficient are almost restored but the mobility of the carriers remains low and a 30% drop in thermal conductivity is still effective (k(total) similar to 8.5 Wm(-1).K-1). This study shows that control defect engineering with defects introduced by irradiation using noble gases in a thermoelectric coating can be an attractive method to enhance the figure of merit of thermoelectric materials.

    Fulltekst (pdf)
    fulltext
  • 214.
    Burcea, Razvan
    et al.
    Univ Poitiers, France.
    Bouteiller, Hugo
    Univ Poitiers, France.
    Hurand, Simon
    Univ Poitiers, France.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Barbot, Jean-Francois
    Univ Poitiers, France.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Effect of induced defects on conduction mechanisms of noble-gas-implanted ScN thin films2023Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 134, nr 5, artikkel-id 055107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Noble-gas implantation was used to introduce defects in n-type degenerate ScN thin films to tailor their transport properties. The electrical resistivity increased significantly with the damage levels created, while the electron mobility decreased regardless of the nature of the ion implanted and their doses. However, the transport property characterizations showed that two types of defects were formed during implantation, named point-like and complex-like defects depending on their temperature stability. The point-like defects changed the electrical conduction mode from metallic-like to semiconducting behavior. In the low temperature range, where both groups of defects were present, the dominant operative conduction mechanism was the variable range hopping conduction mode. Beyond a temperature of about 400 K, the point-like defects started to recover with an activation energy of 90 meV resulting in a decrease in resistivity, independent of the incident ion. The complex-like defects were, therefore, the only remaining group of defects after annealing above 700 K. These latter, thermally stable at least up to 750 K, introduced deep acceptor levels in the bandgap resulting in an increase in the electrical resistivity with higher carrier scattering while keeping the metallic-like behavior of the sample. The generation of both types of defects, as determined by resistivity measurements, appeared to occur through a similar mechanism within a single collision cascade.

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  • 215.
    Buyanova, Irina A
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material. Linköpings universitet, Tekniska högskolan.
    Izadifard, Morteza
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Seppänen, Timo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Chen, Weimin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Pearton, SJ
    Polimeni, A
    Capizzi, M
    Brandt, MS
    Bihler, C
    Hong, YG
    Tu, CW
    Unusual effects of hydrogen on electronic and lattice properties of GaNP alloys2006Inngår i: Physica. B, Condensed matter, ISSN 0921-4526, E-ISSN 1873-2135, Vol. 376, s. 568-570Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Hydrogen incorporation is shown to cause passivation of various N-related localized states and partial neutralization of N-induced changes in the electronic structure of the GaNxP1-x alloys with x < 0.008. According to the performed X-ray diffraction measurements, the hydrogenation is also found to cause strong expansion of the GaNP lattice which even changes from a tensile strain in the as-grown GaNP epilayers to a compressive strain in the post-hydrogenated structures with the highest H concentration. By comparing results obtained using two types of hydrogen treatments, i.e. by implantation from a Kaufman source and by using a remote dc H plasma, the observed changes are shown to be inherent to H due to its efficient complexing with N atoms, whereas possible effects of implantation damage are only marginal. (c) 2005 Elsevier B.V. All rights reserved.

  • 216.
    Buyanova, Irina
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Izadifard, Morteza
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Chen, Wei Min
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Felici, M.
    Polimeni, A.
    Capizzi, M.
    Hong, Y.G.
    Xin, H.P.
    Tu, C.W.
    Unusual effects of hydrogen in GaNP alloys: A general property of dilute nitrides2005Inngår i: 2005 MRS Spring Meeting,2005, 2005, s. 135-Konferansepaper (Annet vitenskapelig)
  • 217.
    Buyanova, Irina
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Izadifard, Morteza
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Ivanov, Ivan Gueorguiev
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Materiefysik.
    Birch, Jens
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Chen, Weimin
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Funktionella elektroniska material.
    Polimeni, A.
    Capizzi, M.
    Hong, Y. G.
    Tu, C. W.
    Effects of hydrogen on electronic and crystalline structure of GaNP2004Inngår i: EMRS-2004 Spring Meeting,2004, 2004Konferansepaper (Annet vitenskapelig)
  • 218.
    Byeon, Ayeong
    et al.
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA; Korea Adv Institute Science and Technology, South Korea.
    Zhao, Meng-Qiang
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Ren, Chang E.
    Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Halim, Joseph
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Drexel University, PA 19104 USA; Drexel University, PA 19104 USA.
    Kota, Sankalp
    Drexel University, PA 19104 USA.
    Urbankowski, Patrick
    Drexel University, PA 19104 USA.
    Anasori, Babak
    Drexel University, PA 19104 USA.
    Barsoum, Michel W.
    Drexel University, PA 19104 USA.
    Gogotsi, Yury
    Drexel University, PA 19104 USA.
    Two-Dimensional Titanium Carbide MXene As a Cathode Material for Hybrid Magnesium/Lithium-Ion Batteries2017Inngår i: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 9, nr 5, s. 4296-4300Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    As an alternative to pure lithium-ion, Lit, systems, a hybrid magnesium, Mg2+, and Li+ battery can potentially combine the high capacity, high voltage, and fast Li+ intercalation of Li-ion battery cathodes and the high capacity, low cost, and dendrite-free Mg metal anodes. Herein, we report on the use of two-dimensional titanium carbide, Ti3C2Tx (MXene), as a cathode in hybrid Mg2+/Li+ batteries, coupled with a Mg metal anode. Free-standing and flexible Ti3C2Tx/carbon nanotube composite "paper" delivered-,100 mAh at 0.1 C and similar to 50 mAh g(-1) at 10 C. At 1 C the capacity was maintained for amp;gt;500 cycles at 80 mAh g(-1). The Mo2CTx MXene also demonstrated good performance as a cathode material in this hybrid battery. Considering the variety of available MXenes, this work opens the door for exploring a new large family of 2D materials with high electrical conductivity and large intercalation capacity as cathodes for hybrid Mg2+/Li+ batteries.

  • 219.
    Cabioch, Thierry
    et al.
    University of Poitiers, France.
    Alkazaz, Malaz
    University of Poitiers, France.
    Beaufort, Marie-France
    University of Poitiers, France.
    Nicolai, Julien
    University of Poitiers, France.
    Eyidi, Dominique
    University of Poitiers, France.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. University of Poitiers, France.
    Ti2AlN thin films synthesized by annealing of (Ti plus Al)/AlN multilayers2016Inngår i: Materials research bulletin, ISSN 0025-5408, E-ISSN 1873-4227, Vol. 80, s. 58-63Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Single-phase Ti2AlN thin films were obtained by annealing in vacuum of (Ti + Al)/AIN multilayers deposited at room temperature by magnetron sputtering onto single-crystalline (0001) 4H-SiC and (0001) Al2O3 substrates. In-situ X-ray diffraction experiments combined with ex-situ cross-sectional transmission electron microscopy observations reveal that interdiffusion processes occur in the multilayer at a temperature of similar to 400 degrees C leading to the formation of a (Ti, Al, N) solid solution, having the hexagonal structure of alpha-Ti, whereas the formation of Ti2AlN occurs at 550-600 degrees C. Highly oriented (0002) Ti2AlN thin films can be obtained after an annealing at 750 degrees C. (C) 2016 Elsevier Ltd. All rights reserved.

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  • 220.
    Cabioch, Thierry
    et al.
    University of Poitiers.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mauchamp, Vincent
    University of Poitiers.
    Jaouen, Michel
    University of Poitiers.
    Structural investigation of substoichiometry and solid solution effects in Ti2Al(C-x,N1-x)(y) compounds2012Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 32, nr 8, s. 1803-1811Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The milling, cold compaction and thermal annealing (4 h-1400 degrees C-Ar flow) of Ti, TiC, Al and AlN powders were used to produce Ti2Al(CxN(1-x))(y) compounds with x = 0, 0.25, 0.5, 0.75, 1 and 0.7 andlt;= y andlt;= 1. X-ray diffraction analysis, scanning electron microscopy observations combined with microanalysis confirmed the formation of the almost pure Ti(2)A/CxN(1-x) carbonitrides for y=1 whereas increasing amounts of titanium aluminides were formed when y decreases. Proportions of the different phases deduced from Rietveld refinements of the X-ray diffractograms indicate that no or very poor substoichiometry in carbon was possible in carbide whereas C and N deficiency can be achieved in nitrides and carbonitrides Ti2AlCxN(1-x). Electron Energy Loss Spectroscopy investigations confirm that carbonitrides can have at least 20% of vacancies on the C or N site. The a lattice parameter varies linearly with x whereas it is not the case for the c lattice parameter, its values being lower for the carbonitrides. Furthermore, a strong broadening of the carbonitrides XRD peaks is observed, a phenomenon that can be mainly attributed to C and N concentration gradients inside the samples.

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  • 221.
    Cabioch, Thierry
    et al.
    Université de Poitiers, France.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Mauchamp, Vincent
    Université de Poitiers, France.
    Jaouen, Michel
    Université de Poitiers, France.
    Barsoum, Michel W.
    Université de Poitiers, France and Drexel University, Philadelphia, USA.
    Tailoring of the thermal expansion of Cr2(Alx,Ge1−x)C phases2013Inngår i: Journal of the European Ceramic Society, ISSN 0955-2219, E-ISSN 1873-619X, Vol. 33, nr 4, s. 897-904Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report thermal expansion coefficients of the end members and solid-solution compounds in the Cr2(Alx,Ge1−x)C system. All samples studied were essentially phase-pure Cr2AlxGe1−xC except the Cr2GeC sample, which contained a substantial fraction of Cr5Ge3Cx. X-ray diffraction performed in the 25–800 °C temperature range shows that the in-plane thermal expansion remains essentially constant at about 14 ± 1 × 10−6 K−1 irrespective of Al content. The thermal expansion of the c axis decreases monotonically from 17 ± 1 × 10−6 K−1 for Cr2GeC to ∼12 ± 1 × 10−6 K−1 with increasing Al content. At around the Cr2(Al0.75,Ge0.25)C composition, the thermal expansion coefficients along the two directions are equal; a useful property to minimize thermal residual stresses. This study thus demonstrates that a solid-solution approach is a route for tuning a physical property like the thermal expansion. For completeness, we also include a structure description of the Cr5Ge3Cx phase, which has been reported before but is not well documented. Its space group is P63/mcm and its a and c lattice parameters are 7.14 Å and 4.88 Å, respectively. We also measured the thermal expansion coefficients of the Cr5Ge3Cx phase. They are found to be 16.3 × 10−6 K−1 and 28.4 × 10−6 K−1 along the a and c axes, respectively. Thus, the thermal expansion coefficients of Cr5Ge3Cx are highly anisotropic and considerably larger than those of the Cr2(Alx,Ge1−x)C phases.

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  • 222.
    Calamba, Katherine
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Univ Lorraine, France.
    Barrirero, Jenifer
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Saarland Univ, Germany.
    Joesaar, M. P. Johansson
    SECO Tools AB, Sweden.
    Bruyere, S.
    Univ Lorraine, France.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Pierson, J. F.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Muecklich, F.
    Saarland Univ, Germany.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Growth and high temperature decomposition of epitaxial metastable wurtzite (Ti1-x,Al-x)N(0001) thin films2019Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 688, artikkel-id 137414Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The structure, growth, and phase stability of (Ti1-x,Al-x)N films with high Al content were investigated. (Ti1-x,Al-x)N (x= 0.63 and 0.77) thin films were grown on MgO (111) substrates at 700 degrees C using a UHV DC magnetron sputtering system. The (Ti-0.37,Al-0.63)N film is a single crystal with a cubic NaCl (B1) structure while the (T-i0.23,Al-0.77)N film only shows epitaxial growth of the same cubic phase in the first few atomic layers. With increasing film thickness, epitaxial wurtzite (B4) forms. The thin cubic layer and the wurtzite film has an orientation relationship of c-(Ti-0.23,Al-0.77)N(111)[110]parallel to w-(Ti-0.23,Al-0.77)N(0001)[11 (2) over bar0]. Continued deposition results in a gradual break-down of the epitaxial growth. It is replaced by polycrystalline growth of wurtzite columns with a high degree of 0001 texture, separated by a Tienriched cubic phase. In the as-deposited state, c-(Ti-0.27,Al-0.63)N displays a homogeneous chemical distribution while the w-(Ti-0.23,Al-0.77)N has segregated to Al- and Ti-rich domains. Annealing at 900 degrees C resulted in the spinodal decomposition of the metastable c-(Ti-0.27,Al-0.63)N film and formation of coherent elongated c-AlN and cTi-N-rich domains with an average width of 4.5 +/- 0.2 nm while the width of the domains in the w-(Ti-0.23,Al-0.77)N film only marginally increases to 2.8 +/- 0.1 nm. The slower coarsening rate of the wurtzite structure compared to cubic is indicative of a higher thermal stability.

  • 223.
    Calamba, Katherine
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Univ Lorraine, France.
    Pierson, J. F.
    Univ Lorraine, France.
    Bruyere, S.
    Univ Lorraine, France.
    Le Febvrier, Arnaud
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Barrirero, Jenifer
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. Saarland Univ, Germany.
    Muecklich, F.
    Saarland Univ, Germany.
    Boyd, Robert
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Jöesaar Johansson, Mats
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten. SECO Tools AB, Sweden.
    Odén, Magnus
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Dislocation structure and microstrain evolution during spinodal decomposition of reactive magnetron sputtered heteroepixatial c-(Ti-0.37,Al-0.63)N/c-TiN films grown on MgO(001) and (111) substrates2019Inngår i: Journal of Applied Physics, ISSN 0021-8979, E-ISSN 1089-7550, Vol. 125, nr 10, artikkel-id 105301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Heteroepitaxial c-(Ti-0.37,Al-0.63)N thin films were grown on MgO(001) and MgO(111) substrates using reactive magnetron sputtering. High resolution high-angle annular dark-field scanning transmission electron micrographs show coherency between the film and the substrate. In the as-deposited state, x-ray diffraction reciprocal space maps show a strained epitaxial film. Corresponding geometric phase analysis (GPA) deformation maps show a high stress in the film. At elevated temperature (900 degrees C), the films decompose to form iso-structural coherent c-Al- and c-TiN-rich domains, elongated along the elastically soft amp;lt;100amp;gt; directions. GPA analysis reveals that the c-TiN domains accommodate more dislocations than the c-AlN domains. This is because of the stronger directionality of the covalent bonds in c-AlN compared with c-TiN, making it more favorable for the dislocations to accumulate in c-TiN. The defect structure and strain generation in c-(Ti,Al)N during spinodal decomposition is affected by the chemical bonding state and elastic properties of the segregated domains.

  • 224.
    Cao, Nan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Tech Univ Munich, Germany.
    Yang, Biao
    Tech Univ Munich, Germany.
    Riss, Alexander
    Tech Univ Munich, Germany.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Björk, Jonas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Materialdesign. Linköpings universitet, Tekniska fakulteten.
    Barth, Johannes V.
    Tech Univ Munich, Germany.
    On-surface synthesis of enetriynes2023Inngår i: Nature Communications, E-ISSN 2041-1723, Vol. 14, nr 1, artikkel-id 1255Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Belonging to the enyne family, enetriynes comprise a distinct electron-rich all-carbon bonding scheme. However, the lack of convenient synthesis protocols limits the associated application potential within, e.g., biochemistry and materials science. Herein we introduce a pathway for highly selective enetriyne formation via tetramerization of terminal alkynes on a Ag(100) surface. Taking advantage of a directing hydroxyl group, we steer molecular assembly and reaction processes on square lattices. Induced by O-2 exposure the terminal alkyne moieties deprotonate and organometallic bis-acetylide dimer arrays evolve. Upon subsequent thermal annealing tetrameric enetriyne-bridged compounds are generated in high yield, readily self-assembling into regular networks. We combine high-resolution scanning probe microscopy, X-ray photoelectron spectroscopy and density functional theory calculations to examine the structural features, bonding characteristics and the underlying reaction mechanism. Our study introduces an integrated strategy for the precise fabrication of functional enetriyne species, thus providing access to a distinct class of highly conjugated pi-system compounds. Enetriynes, which belong to the enyne family, are characterized by a distinct electron-rich carbon-bonding scheme. Here, the authors report the formation of enetriynes with high selectivity by tetramerization of terminal alkynes on Ag(100).

    Fulltekst (pdf)
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  • 225.
    Carlberg, M H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Atomistic study of defect generation mechanisms in Mo/W superlattices1996Inngår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 112, nr 1-4, s. 109-111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work we report the investigation of defect generation in Mo/W superlattices (SL). The study has been carried out using molecular dynamics (MD) and the embedded atom (EAM) potential. Mechanisms for the generation of observed defect patterns are proposed.

  • 226.
    Carlberg, M H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Defects and energy accommodation in epitaxial sputter deposited Mo/W superlattices studied by molecular dynamics1998Inngår i: Thin Solid Films, ISSN 0040-6090, E-ISSN 1879-2731, Vol. 317, nr 1-2, s. 10-13Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We report here the results of a Molecular Dynamics-Embedded Atom Method-investigation of the pathways generating point defects in Mo/W superlattices during bombardment with energetic (50 to 200 eV) Ar and Kr neutrals. Energy accommodation coefficients are computed for the different structures and are found to be roughly independent of the incident energy, and substantially higher for structures with Mo on top. Several different types of defects are shown, and two general processes generating those are discussed. Trapping of the incoming noble gas was observed for the case of Kr impinging on structures with Mo as the top monolayer; this is interpreted as an effect of the small mass difference between the Mo and the Kr atoms. An increase in atomic mass of the gas translates into a more disparate behaviour of the studied structures. The energy exchange with the surface layer dictates the behaviour of the superlattice; this is accentuated when bombarding with the heavier gas, Kr. (C) 1998 Elsevier Science S.A.

  • 227.
    Carlberg, M H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Chirita, Valeriu
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Molecular-dynamics studies of defect generation in epitaxial Mo/W superlattices1996Inngår i: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 54, nr 3, s. 2217-2224Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An investigation of defect generation at the interface during growth of epitaxial (100) oriented Mo/W superlattices by ion-assisted deposition has been carried out using molecular-dynamics simulations. The influence of the impact parameter within the irreducible bcc unit cell [001] surface and the incident ion energy on the energy accommodation, the dynamics of energy transfer, and energy dissipation are discussed. A detailed model of the generation of point defects is presented and the influence of materials upon the type and the number of defects as well as the energy accommodation of the superlattice is revealed. It is shown that the behavior of the superlattice as a whole is largely dominated by the material in the surface monolayer.

  • 228.
    Carlberg, M H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Dynamics of self-interstitial structures in body-centred-cubic W studied by molecular dynamics simulation2000Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 12, nr 1, s. 79-86Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study concerns a molecular dynamics (MD) simulation, using the embedded-atom method (EAM), of the self-diffusion of an interstitial in the bcc metal tungsten (W) at 2000 K. It is found that the interstitial moves only along (111) diagonals and that the switches to other nonparallel directions take place through a two-dimensional process. The (011) dumb-bell is central to this process. Movement along the (111) diagonals takes place through (111) crowdions occupying 2-6 lattice sites. The probabilities of a direction switch and a move are 0.249 and 0.751, respectively. Translating the complicated movement mechanism into the simple picture of interstitial hopping between lattice points, the diffusion velocity is calculated to be 520 m s(-1), and the activation energy for the interstitial self-diffusion is calculated to be 0.54 eV/interstitial.

  • 229.
    Carlberg, M H
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Self-interstitial structures in body-centred-cubic W studied by molecular dynamics simulation1999Inngår i: Journal of Physics: Condensed Matter, ISSN 0953-8984, E-ISSN 1361-648X, Vol. 11, nr 34, s. 6509-6514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper reports a simulation study of the detailed structure of an interstitial in a body-centred-cubic (bcc) metal, tungsten (W), using molecular dynamics and the embedded-atom method. Several distinct configurations can be discerned, including the well-known split-interstitial [011] dumb-bell. The [111] crowdion is also observed, as is a set of similar, one-dimensional, defect configurations. These are grouped into a proposed classification scheme, in which the traditional crowdion is revealed as part of a whole family. The defect energies of the various configurations are computed, and comparisons are made with bce iron (Fe) results. The [011] dumb-bell is the energetically most favourable configuration in W. It is found to have a radius of approximately one W lattice constant, 3.16 Angstrom.

  • 230.
    Carlsson, Adam
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik.
    Phase stability and mechanical properties of M4AlB4 (m=Cr, Hf, Mo, Nb, Ta, Ti, V, W, Zr) from first principles2019Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The recent discovery of Cr4AlB4, a laminated ternary metal boride belonging to the family of layered MAB-phases, where the transition metal boride layers are interleaved by an A layer, has spurred theoretical investigation for novel M4AlB4 phases. In this study, first-principles calculations were applied in order to investigate the thermodynamical stability and mechanical properties of M4AB4 where M = Cr, Hf, Mo, Nb, Ta, Ti, V, W, Zr while the A layer was kept fixed as Al. The thermodynamical stability calculations validate the recently discovered Cr4AlB4 phase’s stability and suggest the neighboring phase Mo4AlB4 to be stable. Additionally, the phases Mo3AlB4, Mo2AlB2, Ti4AlB4 and Ti2AlB2 indicates phases close to stable with a formation enthalpy within the range of 0 < ∆H < 25 meV per atom compared to competing phases. Hence dynamical stability investigations were carried out, which indicates Mo4AlB4 to be dynamically stable. The stability of Mo4AlB4 does encourage synthesizing attempts to be kept in mind as a future project. Phase stability trends of the 111, 212, 314 and 414 compositions were discovered, where a 212, 314 and 414 composition is seen to be more stable for an M-element with lower electron configuration. Furthermore, the mechanical properties of the 414 compositions were investigated by systematically straining the unit cell in different directions. The bulk-, shear- and Young’s-modulus were derived and are presented, where Ti4AlB4 demonstrates values similar to the commended Ti2AlC MAX-phase. Finally, ductility plots are presented which purposes a linear trend between the elements of group IV, V and VI. Based on the results, further studies with a focus on the temperature and magnetization’s impact on the stability and mechanical properties are suggested.

    Fulltekst (pdf)
    fulltext
  • 231.
    Carlsson, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Combinatorial T hin F ilm Synthe sis of Cr2AlC; aComparison of Two Sputte ring M e tho ds2012Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    MAX phase materials have unique properties that combine metals and ceramics.These properties stems from the complex structure with extremely strong M-Xbonds and weaker M-A bonds. Physical vapor deposition in form of magnetronsputtering is widely used for thin film syntheses. High Power Impulse MagnetronSputtering (HIPIMS) was introduced in the mid-90s, today it is a state of the artthin film deposition method for researchers all over the world.Combinatorial sputter deposition of Cr2AlC with HIPIMS and direct currentmagnetron sputtering of the chromium target were compared. Aluminum andcarbon were sputtered from individual targets with a shield in between of thethree targets, making the combinatorial method possible.X-ray diffraction showed that Cr2AlC was present at 550oC and scanning elec-tron microscopy showed that there was not big difference in the morphology. Elec-trical measurements indicated that the film deposited with HIPIMS had a signif-icant higher electrical conductivity compared to the film deposited with directcurrent. x-ray photoelectron Spectroscopy gives an idea of the composition of thefilm, in one position there were oxygen through the film, the rest were dense films.By using a combinatorial approach Cr2Al was also found in the films. The twofilms compared deposited with different methods, showed small differences but notthe ones expected.

    Fulltekst (pdf)
    Carlsson - Combinatorial Thin Film Synthesis of Cr2AlC; a Comparison of Two Sputtering Methods
  • 232.
    Chaix-Pluchery, O.
    et al.
    University of Grenoble Alpes, France.
    Thore, Andreas
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten.
    Kota, S.
    Drexel University, PA 19104 USA.
    Halim, Joseph
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten. Drexel University, PA 19104 USA.
    Hu, C.
    Drexel University, PA 19104 USA.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Ouisse, T.
    University of Grenoble Alpes, France.
    Barsoum, M. W.
    Drexel University, PA 19104 USA.
    First-order Raman scattering in three-layered Mo-based ternaries: MoAlB, Mo2Ga2C and Mo2GaC2017Inngår i: Journal of Raman Spectroscopy, ISSN 0377-0486, E-ISSN 1097-4555, Vol. 48, nr 5, s. 631-638Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here, we report, for the first time, on the first-order Raman spectra of the layered Mo-based ternaries: MoAlB, Mo2Ga2C and Mo2GaC. Polycrystalline samples were fabricated, and well-defined Raman spectra were recorded. When the experimental peak positions were compared with those predicted from density functional theory, good agreement was obtained, indirectly validating both. Furthermore, all modes in the three compounds were symmetry assigned. Copyright (c) 2017 John Wiley amp; Sons, Ltd.

    Fulltekst (pdf)
    fulltext
  • 233.
    Champagne, A.
    et al.
    UCLouvain, Belgium.
    Chaix-Pluchery, O.
    Univ Grenoble Alpes, France.
    Ouisse, T.
    Univ Grenoble Alpes, France.
    Pinek, D.
    Univ Grenoble Alpes, France.
    Gelard, I
    Univ Grenoble Alpes, France.
    Jouffret, L.
    Univ Clermont Auvergne, France.
    Barbier, M.
    Univ Grenoble Alpes, France; European Synchrotron Radiat Facil, France.
    Wilhelm, F.
    European Synchrotron Radiat Facil, France.
    Tao, Quanzheng
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Barsoum, M. W.
    Drexel Univ, PA 19104 USA.
    Charlier, J-C
    UCLouvain, Belgium.
    First-order Raman scattering of rare-earth containing i-MAX single crystals (Mo2/3RE1/3)(2)AlC (RE = Nd, Gd, Dy, Ho, Er)2019Inngår i: Physical Review Materials, E-ISSN 2475-9953, Vol. 3, nr 5, artikkel-id 053609Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Herein, we report on the growth of single crystals of various (Mo2/3RE1/3)(2)AlC (RE = Nd, Gd, Dy, Ho, Er) i-MAX phases and their Raman characterization. Using first principles, the wave numbers of the various phonon modes and their relative atomic displacements are calculated and compared to experimental results. Twelve high-intensity Raman peaks are identified as the fingerprint of this new family of rare-earth containing i-MAX phases, thus being a useful tool to investigate their corresponding composition and structural properties. Indeed, while a redshift is observed in the low-wave-number range due to an increase of the rare-earth atomic mass when moving from left to right on the lanthanide row, a blueshift is observed for most of the high-wave-number modes due to a strengthening of the bonds. A complete classification of bond stiffnesses is achieved based on the direct dependence of a phonon mode wave number with respect to the bond stiffness. Finally, STEM images are used to confirm the crystal structure.

    Fulltekst (pdf)
    fulltext
  • 234.
    Chang, Jui-Che
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Controlled growth of metastable Ta3N5 semiconducting films2024Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The semiconductor tritantalum pentanitride (Ta3N5) is a promising material for green energy applications, specifically in the photoelectrolysis of water to produce oxygen and hydrogen. With a bandgap of approximately 2 eV, Ta3N5 is well-suited for efficient solar light absorption across a broad spectrum, and its band positions align favorably with the redox potential of water. Theoretically, this material could achieve a solar-to-hydrogen efficiency of up to 15.9%. However, the intricate nature of the Ta-N compounds and its metastability have limited research into the development of high-quality Ta3N5.   

    In this thesis, the metastable Ta3N5 films were grown using two types of reactive magnetron sputtering techniques, direct current magnetron sputtering (DCMS) and high-power impulse magnetron sputtering (HiPIMS). Several key parameters were found to stabilize the formation of Ta3N5 phase, including the amount of oxygen in a gas mixture of Ar and N2, total working pressure, the Ta2O5 seed layer, and Ar/N2 partial pressure ratio.   

    First, sputter growth of Ta-N film using a gas mixture of Ar and N2 without oxygen gas, only metallic -TaN and ε-TaN phase were formed. After introducing a small amount of oxygen in the process gas (~2% of total working pressure), the oxygen atoms, with higher electronegativity, replace nitrogen atoms to trigger and stabilize the formation of crystalline Ta3N5-type structure. In addition, with a suitable Ar/N2 partial pressure ratio for Ta3N5 formation, a low-degree fiber-textural orthorhombic Ta3N5 film was formed at the total working pressure range from 5 to 30 mTorr. At 40 mTorr total working pressure, the deposited film transforms to O-rich amorphous Ta-O-N compound. Second, the effect of Ta2O5 seed layer on the control of Ta-N phase was studied. The Ta3N5 phase can be grown only with a Ta2O5 seed layer assistance. Without the seed layer, only metallic TaN phases were formed no matter if the film was grown with or without oxygen assistance. Furthermore, domain epitaxial growth of Ta3N5 film on sapphire substrate was achieved through the control of seed layer’s thickness and crystallinity. While the film was grown on an amorphous TaOx seed layer, the Ta3N5 structure becomes polycrystalline. Third, the formation mechanism and epitaxial growth were studied through microstructural analysis in combination of first-principle density-functional theory calculations. Time-dependent growth evolution of Ta3N5 films combined with HRTEM and EDX measurement revealed that the nitridation of Ta2O5 seed layer and Ta-N film deposition occurs simultaneously at the beginning of the Ta3N5 deposition. Further deposition, the Ta3N5 layer was dominated by {00k} domain mixed with (113) domain with a thin TaN layer between Ta3N5 layer and substrate. Last, various Ta-N compounds were grown via controlling the Ar/N2 partial pressure ratio and total working pressure. When the reactive gas was changed from pure Ar to pure nitrogen, the deposited films transformed from Ta metal (mixed with TaOx), TaN, TaN mixed with Ta3N5 to polycrystalline Ta3N5 phase. 

    To summarize the work conducted in this thesis, I have established a reproducible and precise method for cultivating metastable Ta3N5 through the magnetron sputter deposition technique. The elucidated growth mechanism holds promise for synthesizing Ta3N5 on diverse substrates using alternative techniques, ensuring a controlled and adaptable approach. 

    Delarbeid
    1. Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
    Åpne denne publikasjonen i ny fane eller vindu >>Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
    Vise andre…
    2021 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, artikkel-id 126665Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

    sted, utgiver, år, opplag, sider
    ELSEVIER SCIENCE SA, 2021
    Emneord
    Ta3N5; Magnetron sputtering; XRD; XPS; ERDA; Optical absorption spectroscopy
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-173006 (URN)10.1016/j.surfcoat.2020.126665 (DOI)000604750600025 ()
    Merknad

    Funding Agencies|Vetenskapseddet [2018-04198]; Energimyndigheten [46658-1]; Stiftelsen 011e Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; VR-RFI [821-2012-5144, 2017-00646_9]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [RIF14-0053, 5E13-0333]

    Tilgjengelig fra: 2021-01-27 Laget: 2021-01-27 Sist oppdatert: 2023-12-21
    2. Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
    Åpne denne publikasjonen i ny fane eller vindu >>Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
    Vise andre…
    2022 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, artikkel-id 128581Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

    sted, utgiver, år, opplag, sider
    Elsevier, 2022
    Emneord
    Ta3N5, Sputtering, MSE, XRD, XPS, Water splitting, Single crystal
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-188556 (URN)10.1016/j.surfcoat.2022.128581 (DOI)000868328000003 ()
    Merknad

    Funding: Swedish Research Council [2018-04198, 2021-00357]; Swedish Energy Agency [46658-1]; Stiftelsen Olle Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

    Tilgjengelig fra: 2022-09-16 Laget: 2022-09-16 Sist oppdatert: 2023-12-21bibliografisk kontrollert
    3. HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
    Åpne denne publikasjonen i ny fane eller vindu >>HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate
    Vise andre…
    2023 (engelsk)Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 217, artikkel-id 112553Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).

    sted, utgiver, år, opplag, sider
    PERGAMON-ELSEVIER SCIENCE LTD, 2023
    Emneord
    GaN; Magnetron sputtering; HiPIMS; Dislocations; XRCTEM
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-197990 (URN)10.1016/j.vacuum.2023.112553 (DOI)001072124300001 ()
    Forskningsfinansiär
    Swedish Research CouncilSwedish Energy AgencyThe Swedish Foundation for International Cooperation in Research and Higher Education (STINT)Carl Tryggers foundation Olle Engkvists stiftelse
    Merknad

    Funding agencies: This research was funded by Vetenskapsrådet (grant number 2018-04198), Energimyndigheten (grant number 46658-1), Carl Tryggers Stiftelse (grant number CTS 22:2029) and Stiftelsen Olle Engkvist Byggmästare (grant number 197-0210). The Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU 2009-00971) is acknowledged for financial support. We acknowledge STINT foundation, Sweden, for supporting this international collaboration (grant number: MG2019-8485).

    Tilgjengelig fra: 2023-09-20 Laget: 2023-09-20 Sist oppdatert: 2023-12-21
  • 235. Bestill onlineKjøp publikasjonen >>
    Chang, Jui-Che
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Metastable orthorhombic Ta3N5 thin films grown by magnetron sputter epitaxy2022Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The semiconductor tritantalum pentanitride (Ta3N5) is a promising green-energy material for photoelectrolyzing water to produce oxygen and hydrogen owing to its proper bandgap of 2.0 ± 0.2 eV and band positions to redox potential of water. Compare with the conventional setup of water splitting, such as TiO2, Fe2O3, Cu2O, and WO3, the Ta3N5 shows a proper band gap, which leads to a theoretical efficiency as high as 15.9%. However, the complexity of the Ta-N system and the metastability of the Ta3N5 result in the limited research of the growth of high quality stoichiometric Ta3N5.

    Conventionally, the two-step growth of oxidation and nitridation of a metal Ta using thermal annealing in oxygen and ammonia environment is used to produce the Ta3N5. However, the amount of incorporated oxygen in the Ta3N5 samples and film’s thickness and interface are hardly to be controlled, and the use of ammonia as the nitridation gas is harmful to the environment. Hence, in this thesis work, the reactive magnetron sputtering is used to synthesis the Ta3N5, which demonstrates some advantages, such as possibility to grow on a substrate with nanostructure on the surface, a simplification of growth process, usage of environmental-friendly reactive gas, and even scaling up to the industrial application.

    The thesis presents a successful growth of orthorhombic Ta3N5-type Ta-O-N compound thin films on Si and sapphire substrates, specifically Ta3-xN5-yOy, using reactive magnetron sputtering with a gas mixture of Ar, N2, and O2. In the deposition process, the total working pressure was increasing from 5 to 40 mTorr, while keeping same partial pressure ratio (Ar: N2: O2 = 3: 2: 0.1). When the total pressure in the region between 5-30 mTorr, a low-degree fiber-textural Ta3-xN5-yOy films were grown. In addition, with the characterization of elastic recoil detection analysis (ERDA), the atomic fraction of O, N, and Ta of as-grown Ta3-xN5-yOy films were found varying from 0.02 to 0.15, 0.66 to 0.54, and 0.33 to 0.31, respectively, which leads to a b-lattice constant decrease around 1.3 %, shown in X-ray diffraction (XRD) results. For a total working pressure up to 40 mTorr, an amorphous O-rich Ta-O-N compound film was formed mixed with non-stoichiometric TaON and Ta2O5, which further raised the oxygen atomic fraction to ~0.48. The increasing total working pressure results in an increasing band gap from 2.22 to 2.66 eV of Ta3-xN5-yOy films, and further increasing to around 2.96 eV of O-rich Ta-O-N compound films. The mechanism of increasing oxygen atomic fraction in the film is founded correlated with the forming oxide on the Ta target surface during the deposition process due to the strong reactivity of O to Ta by the characterization of optical emission spectroscopy (OES). Moreover, the sputter yield was reduced due to the target poisoning, and which is evidenced by both plasma analysis and depth profile from ERDA.

    A further studies with the deposition parameters for nearly pure Ta3N5 films (oxygen atomic fraction ~2%) was performed using c-axis oriented Al2O3 substrate. In this research, it is found that a Ta2O5 seed layer and a small amount of oxygen were necessary for the growth of Ta3N5. Without the help of seed layer and oxygen, only metallic TaN phases, either mixture of ε- and δ- TaN or δ-TaN were grown, evidenced by X-ray photoelectron spectroscopy (XPS). Furthermore, the structure and phase purity of Ta3N5-phase dominated films was found highly correlated with the thickness of the Ta2O5 seed layer. With the increasing thickness of the seed layer from 5, 9, to 17 nm, the composition of grown films was changed from 111-oriented δ-TaN mixed with c-axis oriented Ta3N5, c-axis oriented Ta3N5, to polycrystalline Ta3N5. In addition, the azimuthal φ-scans in grazing incident geometry demonstrates that the c-axis oriented Ta3N5 contained epitaxially three-variant-orientation domains, in which the a and b planes parallel to the m and a planes of c-axis oriented Al2O3. With the simulation of density functional theory (DFT), the growth of thin seed layers of orthorhombic Ta2O5 (β-Ta2O5) was found promoting by introducing a small amount of oxygen, after calculating the interplay between the topological and energy selection criteria. By the co-action of the mentioned criteria, this already grown Ta2O5 seed layer favored the growth of the orthorhombic Ta3N5 phase. Hence, the mechanism of the domain epitaxial growth of c-axis oriented Ta3N5 on c-axis oriented Al2O3 is attributed to the similar atomic arrangement Ta3N5(001) and β-Ta2O5(201) with a small lattice mismatch around of 2.6% and 4.5%, for the interface of film/seed layer and seed layer/substrate, respectively, and a favorable energetic interaction between involved materials.

    Delarbeid
    1. Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
    Åpne denne publikasjonen i ny fane eller vindu >>Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties
    Vise andre…
    2021 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, artikkel-id 126665Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

    sted, utgiver, år, opplag, sider
    ELSEVIER SCIENCE SA, 2021
    Emneord
    Ta3N5; Magnetron sputtering; XRD; XPS; ERDA; Optical absorption spectroscopy
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-173006 (URN)10.1016/j.surfcoat.2020.126665 (DOI)000604750600025 ()
    Merknad

    Funding Agencies|Vetenskapseddet [2018-04198]; Energimyndigheten [46658-1]; Stiftelsen 011e Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]; VR-RFI [821-2012-5144, 2017-00646_9]; Swedish Foundation for Strategic Research (SSF)Swedish Foundation for Strategic Research [RIF14-0053, 5E13-0333]

    Tilgjengelig fra: 2021-01-27 Laget: 2021-01-27 Sist oppdatert: 2023-12-21
    2. Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
    Åpne denne publikasjonen i ny fane eller vindu >>Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate
    Vise andre…
    2022 (engelsk)Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, artikkel-id 128581Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

    sted, utgiver, år, opplag, sider
    Elsevier, 2022
    Emneord
    Ta3N5, Sputtering, MSE, XRD, XPS, Water splitting, Single crystal
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-188556 (URN)10.1016/j.surfcoat.2022.128581 (DOI)000868328000003 ()
    Merknad

    Funding: Swedish Research Council [2018-04198, 2021-00357]; Swedish Energy Agency [46658-1]; Stiftelsen Olle Engkvist Byggmastare [197-0210]; Linkoping University Library; Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linkoping University [SFO-Mat-LiU 2009-00971]

    Tilgjengelig fra: 2022-09-16 Laget: 2022-09-16 Sist oppdatert: 2023-12-21bibliografisk kontrollert
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  • 236.
    Chang, Jui-Che
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Kostov Gueorguiev, Gueorgui
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Sandström, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Domain epitaxial growth of Ta3N5 film on c-plane sapphire substrate2022Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 443, artikkel-id 128581Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tritantalum pentanitride (Ta3N5) semiconductor is a promising material for photoelectrolysis of water with high efficiency. Ta3N5 is a metastable phase in the complex system of TaN binary compounds. Growing stabilized single-crystal Ta3N5 films is correspondingly challenging. Here, we demonstrate the growth of a nearly single-crystal Ta3N5 film with epitaxial domains on c-plane sapphire substrate, Al2O3(0001), by magnetron sputter epitaxy. Introduction of a small amount ~2% of O2 into the reactive sputtering gas mixed with N2 and Ar facilitates the formation of a Ta3N5 phase in the film dominated by metallic TaN. In addition, we indicate that a single-phase polycrystalline Ta3N5 film can be obtained with the assistance of a Ta2O5 seed layer. With controlling thickness of the seed layer smaller than 10 nm and annealing at 1000 °C, a crystalline β phase Ta2O5 was formed, which promotes the domain epitaxial growth of Ta3N5 films on Al2O3(0001). The mechanism behind the stabilization of the orthorhombic Ta3N5 structure resides in its stacking with the ultrathin seed layer of orthorhombic β-Ta2O5, which is energetically beneficial and reduces the lattice mismatch with the substrate.

    Fulltekst (pdf)
    fulltext
  • 237.
    Chang, Jui-Che
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eriksson, Fredrik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Sortica, Mauricio A.
    Uppsala Univ, Sweden.
    Greczynski, Grzegorz
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Bakhit, Babak
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hu, Zhang-Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Molekylär ytfysik och nanovetenskap. Linköpings universitet, Tekniska fakulteten.
    Primetzhofer, Daniel
    Uppsala Univ, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Orthorhombic Ta3-xN5-yOy thin films grown by unbalanced magnetron sputtering: The role of oxygen on structure, composition, and optical properties2021Inngår i: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 406, artikkel-id 126665Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Direct growth of orthorhombic Ta3N5-type Ta-O-N compound thin films, specifically Ta3-xN5-yOy, on Si and sapphire substrates with various atomic fractions is realized by unbalanced magnetron sputtering. Low-degree fiber-textural Ta3-xN5-yOy films were grown through reactive sputtering of Ta in a gas mixture of N-2, Ar, and O-2 with keeping a partial pressure ratio of 3:2:0.1 in a total working pressure range of 5-30 mTorr. With increasing total pressure from 5 to 30 mTorr, the atomic fraction of O in the as-grown Ta3-xN5-yOy films was found to increase from 0.02 to 0.15 while that of N and Ta decrease from 0.66 to 0.54 and 0.33 to 0.31, respectively, leading to a decrease in b lattice constant up to around 1.3%. Metallic TaNx phases were formed without oxygen. For a working pressure of 40 mTorr, an amorphous, O-rich Ta-N-O compound film with a high O fraction of similar to 0.48, was formed, mixed with non-stoichiometric TaON and Ta2O5. By analyzing the plasma discharge, the increasing O incorporation is associated with oxide formation on top of the Ta target due to a higher reactivity of Ta with O than with N. The increase of O incorporation in the films also leads to a optical bandgap widening from similar to 2.22 to similar to 2.96 eV, which is in agreement with the compositional and structural changes from a crystalline Ta3-xN5-yOy to an amorphous O-rich Ta-O-N compound.

    Fulltekst (pdf)
    fulltext
  • 238.
    Chang, Jui-Che
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Tseng, Eric Nestor
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lo, Yi-Ling
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Nayak, Sanjay Kumar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Nanostrukturerade material. Linköpings universitet, Tekniska fakulteten.
    Lundin, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och ytbeläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Persson, Per O. Å.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Horng, Ray-Hua
    National Yang Ming Chiao Tung University, Hsinchu, 30010, Taiwan.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Birch, Jens
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Hsiao, Ching-Lien
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    HiPIMS-grown AlN buffer for threading dislocation reduction in DC-magnetron sputtered GaN epifilm on sapphire substrate2023Inngår i: Vacuum, ISSN 0042-207X, E-ISSN 1879-2715, Vol. 217, artikkel-id 112553Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Gallium nitride (GaN) epitaxial films on sapphire (Al2O3) substrates have been grown using reactive magnetron sputter epitaxy with a liquid Ga target. Threading dislocations density (TDD) of sputtered GaN films was reduced by using an inserted high-quality aluminum nitride (AlN) buffer layer grown by reactive high power impulse magnetron sputtering (R-HiPIMS) in a gas mixture of Ar and N2. After optimizing the Ar/N2 pressure ratio and deposition power, a high-quality AlN film exhibiting a narrow full-width at half-maximum (FWHM) value of the double-crystal x-ray rocking curve (DCXRC) of the AlN(0002) peak of 0.086° was obtained by R-HiPIMS. The mechanism giving rise the observed quality improvement is attributed to the enhancement of kinetic energy of the adatoms in the deposition process when operated in a transition mode. With the inserted HiPIMS-AlN as a buffer layer for direct current magnetron sputtering (DCMS) GaN growth, the FWHM values of GaN(0002) and (10 1‾ 1) XRC decrease from 0.321° to 0.087° and from 0.596° to 0.562°, compared to the direct growth of GaN on sapphire, respectively. An order of magnitude reduction from 2.7 × 109 cm−2 to 2.0 × 108 cm−2 of screw-type TDD calculated from the FWHM of the XRC data using the inserted HiPIMS-AlN buffer layer demonstrates the improvement of crystal quality of GaN. The result of TDD reduction using the HiPIMS-AlN buffer was also verified by weak beam dark-field (WBDF) cross-sectional transmission electron microscopy (TEM).

    Fulltekst (pdf)
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  • 239.
    Chang, Lin
    et al.
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    He, Tingting
    Shanghai Univ, Peoples R China.
    Chen, Zhu
    Shanghai Univ, Peoples R China.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Multi-surface phase-shifting algorithm using the window function fitted by the nonlinear least squares method2022Inngår i: Journal of Modern Optics, ISSN 0950-0340, E-ISSN 1362-3044, Vol. 69, nr 3, s. 160-171Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A multi-surface phase demodulation algorithm is proposed to measure surfaces of the transparent plate simultaneously. A non-linear least-squares method based on the trust region is utilized to fit the window function derived from the characteristic polynomials. The fitted window function requires fewer parameters and has a flexible form, which means the window length can be stretched freely and used flexibly. Then, a multi-surface phase demodulation technique combining the discrete Fourier principle and the fitted window function is investigated, allowing simultaneous reconstruction of the measured front surface, rear surface, and thickness variation. During the implementation of our algorithm, the processing time for the interferograms with 850x850 pixels is around 5.1s. Measurement errors caused by several factors are analyzed, including wavelength-tuning error, frequency order error, cavity length error, and average thickness error. The experimental result on a rectangular transparent plate further verifies the effectiveness of our algorithm.

  • 240.
    Chang, Lin
    et al.
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    He, Tingting
    Shanghai Univ, Peoples R China.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Multisurface Interferometric Algorithm and Error Analysis With Adaptive Phase Shift Matching2022Inngår i: IEEE Transactions on Instrumentation and Measurement, ISSN 0018-9456, E-ISSN 1557-9662, Vol. 71, artikkel-id 1001013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To simultaneously measure topographies of both surfaces of a transparent plate through wavelength-tuning interferometry at arbitrary cavity lengths, a flexible phase shift matching algorithm (FPSMA) is proposed. The FPSMA includes two parts: 1) taking the four-term third-order Nuttall window as an example, a phase demodulation approach is designed and analyzed for extracting the harmonic phases of the front surface, rear surface, and thickness variation of the measured plate and 2) based on the residual error analysis of the developed 5N-Nuttall algorithm for different cavity length coefficients M and the phase-shifting parameters N , a parameter-change technique that allows the developed phase demodulation approach is applied to arbitrary cavity lengths by adaptively changing the phase shifts and frames of the captured interferograms. By this technique, the algorithm failures due to the spectral aliasing of harmonics can be avoided effectively and conveniently, and then the correct phase demodulation can be ensured. Besides, using the developed method, when the values of N or M are chosen in advance, the corresponding available measurement ranges can be given. Besides, the relationship between the window length and the measurement limitation of the measurable thinnest optical thickness is investigated. Considering the common linear and nonlinear errors in the wavelength-shifting process, the error analysis of FPSMA is performed and discussed for situations close to reality. The comparative studies and the experimental results of two transparent parallel plates also support the performance of the developed FPSMA.

  • 241.
    Charalampopoulou, Evangelia
    et al.
    SCK CEN, Belgium; Univ Antwerp, Belgium.
    Lambrinou, Konstantina
    SCK CEN, Belgium; Univ Huddersfield, England.
    Van der Donck, Tom
    Katholieke Univ Leuven, Belgium.
    Paladino, Boris
    Ist Italiano Tecnol, Italy.
    Di Fonzo, Fabio
    Ist Italiano Tecnol, Italy.
    Azina, Clio
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Eklund, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Mraz, Stanislav
    Rhein Westfal TH Aachen, Germany.
    Schneider, Jochen M.
    Rhein Westfal TH Aachen, Germany.
    Schryvers, Dominique
    Univ Antwerp, Belgium.
    Delville, Remi
    SCK CEN, Belgium.
    Early stages of dissolution corrosion in 316L and DIN 1.4970 austenitic stainless steels with and without anticorrosion coatings in static liquid lead-bismuth eutectic (LBE) at 500 degrees C2021Inngår i: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 178, artikkel-id 111234Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work addresses the early stages (&lt;= 1000 h) of the dissolution corrosion behavior of 316L and DIN 1.4970 austenitic stainless steels in contact with oxygen-poor (C-O &lt; 10(-8) mass%), static liquid lead-bismuth eutectic (LBE) at 500 degrees C for 600-1000 h. The objective of this study was to determine the relative early-stage resistance of the uncoated steels to dissolution corrosion and to assess the protectiveness of select candidate coatings (Cr2AlC, Al2O3, V2AlxCy). The simultaneous exposure of steels with intended differences in microstructure and thermomechanical state showed the effects of steel grain size, density of annealing/deformation twins, and secondary precipitates on the steel dissolution corrosion behavior. The findings of this study provide recommendations on steel manufacturing with the aim of using the steels to construct Gen-IV lead-cooled fast reactors.

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    fulltext
  • 242.
    Chen, Dingfu
    et al.
    Shanghai Univ, Peoples R China.
    Peng, Junzheng
    Jinan Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Asundi, Anand
    Nanyang Technol Univ, Singapore.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Measurement of High Numerical Aperture Cylindrical Surface with Iterative Stitching Algorithm2018Inngår i: Applied Sciences, E-ISSN 2076-3417, Vol. 8, nr 11, artikkel-id 2092Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    There are some limitations in null test measurements in stitching interferometry. In order to meet the null test conditions, the moving distance between the sub-apertures often deviates from the theoretical preset distance, which leads to a position deviation of sub-apertures when measured. To overcome this problem, an algorithm for data processing is proposed in this paper. An optimal estimation of the deviation between sub-apertures is used to update their positions, and then a new overlapped region is obtained and again optimized. This process is repeated until the algorithm converges to an acceptable tolerance, and finally exact stitching is realized. A cylindrical lens was taken as an object for experimental examination of the proposed method. The obtained results demonstrate the validity, reliability, and feasibility of our iterative stitching algorithm.

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    fulltext
  • 243.
    Chen, Dingfu
    et al.
    Shanghai Univ, Peoples R China.
    Wang, Chen
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Wu, Xin
    Shanghai Univ Engn Sci, Peoples R China.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Bayesian uncertainty evaluation of stitching interferometry for cylindrical surface2020Inngår i: Measurement, ISSN 0263-2241, E-ISSN 1873-412X, Vol. 157, artikkel-id 107626Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Uncertainty evaluation is one of the most important concepts in metrological characterizations. This paper proposes a method for uncertainty evaluation of measurements of cylindrical surfaces by means of stitching interferometry. The proposed method is based on the Bayesian statistical analysis. The prior deviation for a tested surface is determined by both calculation of standard deviation through multiple measurements of a single sub-aperture and calibration of the optical system error. The probability distribution functions (PDF) of the prior and real misalignment error and measured data of the aperture are derived according to the stitching model. Simulated observations are approximated with the Gibbs Sampler using the Markov Chain Monte Carlo (MCMC) method. Our proposed method is a promising alternative to the ordinary least square technique (LST) with the maximum likelihood estimation (MLE) for obtaining the uncertainty of the misalignment and measurement error in the stitching results. Moreover, it can take the inevitable environment errors into account. The prediction of the uncertainty interval makes our method more attractive in industrial applications. (C) 2020 Elsevier Ltd. All rights reserved.

  • 244.
    Chen, Dingfu
    et al.
    Shanghai Univ, Peoples R China.
    Yin, Zhijun
    Shanghai Univ, Peoples R China.
    Chen, Zhu
    Shanghai Univ, Peoples R China.
    Valyukh, Sergiy
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Yu, Yingjie
    Shanghai Univ, Peoples R China.
    Stitching interferometry of cylindrical surface2022Inngår i: Optics and lasers in engineering, ISSN 0143-8166, E-ISSN 1873-0302, Vol. 157, artikkel-id 107114Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High resolution and high precision are advantages of measuring cylindrical objects employing stitching interferometry. However, due to errors in the cylinder position in a measurement procedure, it is difficult to ensure the accuracy of a macroscopic shape contour and surface waviness contour of the workpiece of the stitching results. To overcome this problem, we proposed a new strategy of stitching interferometry for cylindricity calibration. The measuring process is divided into two parts to measure the macroscopic shape and waviness contour, respectively. Finally, the two measurement results are merged to produce an accurate and complete 360 degrees form map. Besides, we build a two-dimensional Gaussian filter weighting function for a cylindrical profile according to its special shape characteristic. To express the stitching results more precisely, we provide the uncertainty map and power spectral density of the stitching results. An experiment is carried out by taking a ceramic plug gage as the workpiece. The results demonstrate the excellent performance of our method in analyzing the characteristic of the cylindrical profile and show good agreement with such by using cylindricity measuring instruments.

  • 245.
    Chen, Ding-Yuan
    et al.
    SweGaN AB, Linkoping, Sweden; Chalmers Univ Technol, Sweden.
    Persson, Axel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. TheMAC, Sweden; Lund Univ, Sweden; Lund Univ, Sweden.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Chen, Jr-Tai
    SweGaN AB, Linkoping, Sweden.
    Rorsman, Niklas
    Chalmers Univ Technol, Sweden.
    Structural investigation of ultra-low resistance deeply recessed sidewall ohmic contacts for AlGaN/GaN HEMTs based on Ti/Al/Ti-metallization2023Inngår i: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 38, nr 10, artikkel-id 105006Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This study presents a novel approach to forming low-resistance ohmic contacts for AlGaN/GaN HEMTs. The optimized contacts exhibit an outstanding contact resistance of approximately 0.15 & omega;& BULL;mm. This is achieved by firstly recessing the barrier of the heterostructure to a depth beyond the channel. In this way, the channel region is exposed on the sidewall of the recess. The coverage of the Ti/Al/Ti ohmic metalization on the sidewall is ensured through tilting of the sample during evaporation. The annealing process is performed at a low temperature of 550 & DEG;C. The approach does not require precise control of the recess etching. Furthermore, the method is directly applicable to most barrier designs in terms of thickness and Al-concentration. The impact of recessed sidewall angle, thickness and ratio of Ti and Al layers, and the annealing procedure are investigated. Structural and chemical analyses of the interface between the ohmic contacts and epi-structure indicate the formation of ohmic contacts by the extraction of nitrogen from the epi-structure. The approach is demonstrated on HEMT-structures with two different barrier designs in terms of Al-concentration and barrier thickness. The study demonstrate large process window in regard to recess depth and duration of the annealing as well as high uniformity of the contact resistance across the samples, rendering the approach highly suitable for industrial production processes.

  • 246.
    Chen, Ding-Yuan
    et al.
    SweGaN AB, Linkoping, Sweden; Chalmers Univ Technol, Sweden.
    Persson, Axel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Wen, Kai-Hsin
    SweGaN AB, Linkoping, Sweden; Chalmers Univ Technol, Sweden.
    Sommer, Daniel
    United Monolith Semicond GmbH, Germany.
    Grunenputt, Jan
    United Monolith Semicond GmbH, Germany.
    Blanck, Herve
    United Monolith Semicond GmbH, Germany.
    Thorsell, Mattias
    Chalmers Univ Technol, Sweden.
    Kordina, Olof
    SweGaN AB, Linkoping, Sweden.
    Darakchieva, Vanya
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska fakulteten. Lund Univ, Sweden; Lund Univ, Sweden.
    Persson, Per O A
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Chen, Jr-Tai
    SweGaN AB, Linkoping, Sweden.
    Rorsman, Niklas
    Chalmers Univ Technol, Sweden.
    Impact of in situ NH3 pre-treatment of LPCVD SiN passivation on GaN HEMT performance2022Inngår i: Semiconductor Science and Technology, ISSN 0268-1242, E-ISSN 1361-6641, Vol. 37, nr 3, artikkel-id 035011Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The impact on the performance of GaN high electron mobility transistors (HEMTs) of in situ ammonia (NH3) pre-treatment prior to the deposition of silicon nitride (SiN) passivation with low-pressure chemical vapor deposition (LPCVD ) is investigated. Three different NH3 pre-treatment durations (0, 3, and 10 min) were compared in terms of interface properties and device performance. A reduction of oxygen (O) at the interface between SiN and epi-structure is detected by scanning transmission electron microscopy (STEM )-electron energy loss spectroscopy (EELS) measurements in the sample subjected to 10 min of pre-treatment. The samples subjected to NH3 pre-treatment show a reduced surface-related current dispersion of 9% (compared to 16% for the untreated sample), which is attributed to the reduction of O at the SiN/epi interface. Furthermore, NH3 pre-treatment for 10 min significantly improves the current dispersion uniformity from 14.5% to 1.9%. The reduced trapping effects result in a high output power of 3.4 W mm(-1) at 3 GHz (compared to 2.6 W mm(-1) for the untreated sample). These results demonstrate that the in situ NH3 pre-treatment before LPCVD of SiN passivation is critical and can effectively improves the large-signal microwave performance of GaN HEMTs.

  • 247.
    Chen, Jr-Tai
    et al.
    SweGaN AB, Teknikringen 8D, Linköping, Sweden.
    Bergsten, Johan
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Janzén, Erik
    SweGaN AB, Teknikringen 8D, Linköping, Sweden.
    Thorsell, Mattias
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden.
    Hultman, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Rorsman, Niklas
    Department of Microtechnology and Nanoscience, Chalmers University of Technology, Gothenburg, Sweden.
    Kordina, Olof
    SweGaN AB, Teknikringen 8D, Linköping, Sweden.
    A GaN-SiC hybrid material for high-frequency and power electronics2018Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 113, nr 4, artikkel-id 041605Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We demonstrate that 3.5% in-plane lattice mismatch between GaN (0001) epitaxial layers and SiC (0001) substrates can be accommodated without triggering extended defects over large areas using a grain-boundary-free AIN nucleation layer (NL). Defect formation in the initial epitaxial growth phase is thus significantly alleviated, confirmed by various characterization techniques. As a result, a high-quality 0.2-mu m thin GaN layer can be grown on the AIN NL and directly serve as a channel layer in power devices, like high electron mobility transistors (HEMTs). The channel electrons exhibit a state-of-the-art mobility of amp;gt;2000 cm(2)/V-s, in the AlGaN/GaN heterostructures without a conventional thick C- or Fe-doped buffer layer. The highly scaled transistor processed on the heterostructure with a nearly perfect GaN-SiC interface shows excellent DC and microwave performances. A peak RF power density of 5.8 W/mm was obtained at V-DSQ = 40 V and a fundamental frequency of 30 GHz. Moreover, an unpassivated 0.2-mu m GaN/AIN/SiC stack shows lateral and vertical breakdowns at 1.5 kV. Perfecting the GaN-SiC interface enables a GaN-SiC hybrid material that combines the high-electron-velocity thin GaN with the high-breakdown bulk SiC, which promises further advances in a wide spectrum of high-frequency and power electronics.

    Fulltekst (pdf)
    fulltext
  • 248.
    Chen, Jr-Tai
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Persson, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Persson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Kordina, Olle
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan. Classic WBG Semiconductors AB, LEAD, Sweden.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Growth optimization of AlGaN/GaN HEMT structure on 100 mm SiC substrate: Utilizing bottom-to-top approachManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    The structure of high electron mobility transistors (HEMTs) based on group-III nitride materials generally consists of three important blocks; a nucleation layer, a semi-insulating (SI) GaN buffer layer, and active layers. In this work, we present an overall growth optimization, which leads to superior crystalline quality and ultra-low thermal boundary resistance (TBR) of a 35-nm AlN nucleation layer, excellent crystalline quality of carbon-doped GaN buffer layer, and high mobility (> 2000 cm2/Vs) of two-dimensional gas (2DEG) in a simple AlGaN/GaN heterostructure grown on a SI SiC substrate.

  • 249.
    Chen, Jr-Tai
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Persson, Ingemar
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Nilsson, Daniel
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Hsu, Chih-Wei
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Palisaitis, Justinas
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Forsberg, Urban
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Persson, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska högskolan.
    Janzén, Erik
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Halvledarmaterial. Linköpings universitet, Tekniska högskolan.
    Room-Temperature mobility above 2200 cm2/V.s of two-dimensional electron gas in a sharp-interface AlGaN/GaN heterostructure2015Inngår i: Applied Physics Letters, ISSN 0003-6951, E-ISSN 1077-3118, Vol. 106, nr 25, artikkel-id 251601Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A high mobility of 2250 cm2/V·s of a two-dimensional electron gas (2DEG) in a metalorganic chemical vapor deposition-grown AlGaN/GaN heterostructure was demonstrated. The mobility enhancement was a result of better electron confinement due to a sharp AlGaN/GaN interface, as confirmed by scanning transmission electron microscopy analysis, not owing to the formation of a traditional thin AlN exclusion layer. Moreover, we found that the electron mobility in the sharp-interface heterostructures can sustain above 2000 cm2/V·s for a wide range of 2DEG densities. Finally, it is promising that the sharp-interface AlGaN/GaN heterostructure would enable low contact resistance fabrication, less impurity-related scattering, and trapping than the AlGaN/AlN/GaN heterostructure, as the high-impurity-contained AlN is removed.

    Fulltekst (pdf)
    fulltext
  • 250.
    Chen, Liugang
    et al.
    Katholieke Univ Leuven, Belgium.
    Dahlqvist, Martin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lapauw, Thomas
    Katholieke Univ Leuven, Belgium; SCK CEN, Belgium.
    Tunca, Bensu
    Katholieke Univ Leuven, Belgium; SCK CEN, Belgium.
    Wang, Fei
    Katholieke Univ Leuven, Belgium.
    Lu, Jun
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Meshkian, Rahele
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Lambrinou, Konstantina
    SCK CEN, Belgium.
    Blanpain, Bart
    Katholieke Univ Leuven, Belgium.
    Vleugels, Jozef
    Katholieke Univ Leuven, Belgium.
    Rosén, Johanna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Tunnfilmsfysik. Linköpings universitet, Tekniska fakulteten.
    Theoretical Prediction and Synthesis of (Cr2/3Zr1/3)(2)AIC i-MAX Phase2018Inngår i: Inorganic Chemistry, ISSN 0020-1669, E-ISSN 1520-510X, Vol. 57, nr 11, s. 6237-6244Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Guided by predictive theory, a new compound with chemical composition (Cr2/3Zr1/3)(2)AlC was synthesized by hot pressing of Cr, ZrH2, Al, and C mixtures at 1300 degrees C. The crystal structure is monoclinic of space group C2/c and displays in-plane chemical order in the metal layers, a so-called i-MAX phase. Quantitative chemical composition analyses confirmed that the primary phase had a (Cr2/3Zr1/3)(2)AlC stoichiometry, with secondary Cr2AlC, AlZrC2, and ZrC phases and a small amount of Al-Cr intermetallics. A theoretical evaluation of the (Cr2/3Zr1/3)(2)AlC magnetic structure was performed, indicating an antiferromagnetic ground state. Also (Cr2/3Zr1/3)(2)AlC, of the same structure, was predicted to be stable.

2345678 201 - 250 of 2022
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